1. Field of the Invention
The present invention relates to an electrically operated camera, particularly one having a disabling device for disabling the picture taking operation when the voltage of the power source that control the shutter is lower than a predetermined value.
2. Description of the Prior Art
U.S. Pat. No. 3,856,393 discloses a camera having the so-called electric shutter which responds to the camera's power source voltage being lower than a predetermined value by preventing an exposure control magnet from operating so as to block depression of the shutter button and disable the photographic action. This disabling action is used because, in this kind of camera, there is concern that the exposure control cannot be carried out with certainty when the camera's power source has a voltage lower than a predetermined value.
However, the aforementioned conventional disabling device operates so that when the power source voltage is lower than the predetermined value, the shutter button is stopped in its path by a member operatively engaged with the depression of the shutter button so as to prevent the start of the photographic process. However, if the shutter button is depressed too quickly, the shutter button cannot be caught and, in such a case, the photographic action could be started anyway. Also, such a construction requires that the release stroke of the shutter button be long. This is inconvenient in that may result in a heavy shutter button which hinders improvement in the operability of the camera.
Proposals have been made for a camera using a sequence control circuit which detects the power source voltage and disables the transfer to a subsequent photographic sequence. Such sequence control circuits have a complicated structure and result in high production costs. Furthermore, the sequence control circuit must be supplied with power while the power source is driving other photographic operating devices. This is very likely to lower the power supply voltage when power is supplied to a drive motor in an auto focusing sequence or in a film winding sequence and thereby may cause erroneous operation of the sequence control circuit. For this reason it has been common practice to provide a special compensating circuit or a low-priced penlite battery etc. and to increase the voltage by a booster circuit.